Getting Down and Dirty About Soap

I think it goes without saying that we all enjoy being clean – at least once in awhile, right? And I think most of us use some sort of soap. But, do you know soap?

If you take a glance at the back of a bar of soap in the grocery store, you probably notice sodium lauryl sulfate (SLS) as one of the first ingredients. SLS is considered a detergent and can be an irritant to the eyes. If continue down the ingredient list, you may feel like you need a chemistry degree to understand what in the world is in it! And detergent cleans my clothes, not my body.

I started making soap for several reasons, the main one being that it fills my need of applying my chemistry experience with something useful and fun for my family and friends (and now customers at the market!). I love talking about making soap. I love making soap. I love using soap. I pretty much just love soap!

House on the Hill Soap Co set up at the market.

There is evidence from 2800 BC on a Babylonian tablet of a soap like substance being produced. And there is also evidence that the ancient Egyptians bathed regularly with a substance made from animal and vegetable oils combined with an alkali salt. So, it seems clear that soap has played an important role in history, helping to keep people clean and reduce the spread of disease.

I’ve had some really enlightening conversations with some older gentlemen who have stopped by my tent telling me that they remembered stirring the soap for their mothers and grandmothers. Rendered fats from butchered animals on the farm and lye made from wood ashes were used by many of our ancestors to make soap.

I have also had some interesting conversations with other people on what soap actually IS. I’ve had people ask me if I make lye soap or goat milk soap. And I’ve had to explain that lye soap is NOT bad and will not harm your skin. And lye is really quite benign to work with, given you use the proper precautions.

Ok, ok…now what is lye? In modern soap making, lye is sodium hydroxide, or more commonly seen as drain cleaner. It’s somewhat difficult to obtain in a store and many stores require your driver’s license information because, well…lye is also used in the making of methamphetamine. But, have no fear – the lye is completely transformed in the soap making process. As a soap maker, I use proper protective equipment, namely safety glasses.

In chemist jargon, soap is a salt of a fatty acid. There is a reaction of fats, whether they be animal or vegetable in nature, and a strong base, which is lye. This reaction is called saponification. In the soap making process, the fats are heated until melted and mixed with a lye and a liquid, generally water or milk. During the process, the lye reacts completely with the fats and is transformed into the end product, which is a hard soap.

There are generally two methods for making soap, cold process and hot process. Each method has advantages and disadvantages and it is generally the preference of the soap maker as to which method is employed. The choice of which fats to use can be fun and a chemistry experiment within itself. If you see “castile soap” – know that it is completely olive oil based. Each fat gives a unique property to the end soap – moisturizing, hardness, and lather just to name the main attributes.

I choose to employ the hot process method. For me, the biggest attraction to using the hot process method is the fact that the soap is ready to be used the day after it is made. In cold process soap, the soap needs 6 weeks to “cure” or to allow the soap to come to a reasonable pH as to not be harmful to skin. Because hot process uses heat to speed this curing time, the soap is ready faster. In order to test for safety, I use phenolphthalein to ensure the soap is no longer caustic and safe to use.

Lemon Poppy Seed soap before being put in a mold. It looks like muffin batter!

There are numerous fats that can be used in soap making, but I have chosen to keep my soap more local. I obtain fat from local cows and pigs and then further render the fat down into tallow and lard. When an animal was butchered on the farm, every last piece was used. Lard was used for cooking and often times tallow was used to make candles. Nowadays, however, the fat is just a waste product of the butchering process. Rendering adds an extra step to the process, but I appreciate knowing where the fat comes from.